Despite Green Image, Biofuels Manufacturing Releases Large Amounts of Hazardous Air Pollutants

Report: Biofuel Makers Report Releasing Almost as Much Hazardous Air Pollution as Oil Refineries, and More of Some Carcinogens 

To listen to audio of the online press conference on June 12, 2024, click here.

Washington, D.C. — Although the rapidly-growing biofuel industry portrays itself as a clean alternative to petroleum-based fuels, biofuel manufacturing plants release almost as much hazardous air pollution as oil refineries – and more of some dangerous pollutants, according to a study by the Environmental Integrity Project (EIP).

These pollutants from ethanol, biodiesel and “renewable diesel” manufacturing plants include  formaldehyde (a carcinogen), acetaldehyde (a probable carcinogen), hexane (which can attack the central nervous system and cause dizziness, nausea, and headaches) and acrolein (which can cause nausea, vomiting, diarrhea, lung and eye irritation, and shortness of breath).

The result of these hazardous emissions is that some rural Midwestern communities in Iowa, Illinois, and elsewhere suffer from unhealthy air quality despite having no significant pollution sources around them, other than the smokestacks of ethanol refineries, according to EIP’s new report, “Farm to Fumes: Hazardous Air Pollution from Biofuel Production.

One reason the industry and its emissions are growing so fast – with the number of U.S. ethanol plants multiplying four-fold in the first decade of this century – is because of federal supports and fuel-blending mandates and EPA permitting loopholes that allow even some large ethanol plants to avoid modern pollution control devices.

“Despite its green image, the biofuels industry releases a surprising amount of hazardous air pollution that puts local communities at risk – and this problem is exacerbated by EPA’s lax regulation,” said Courtney Bernhardt, Director of Research for the Environmental Integrity Project. “EPA needs to end its permitting loopholes for large ethanol plants and start requiring the kind of fenceline air pollution monitoring and cleanup actions the agency already requires for oil refineries.”

EIP’s report found that, despite government policies supporting the biofuels industry, biofuel plants frequently violate their air pollution control permits, releasing illegal amounts of contaminants that threaten the health of downwind communities. Biofuel plants also emit large quantities of greenhouse gases for an industry that portrays itself as climate-friendly.

For this report, EIP examined the public records of 191 ethanol manufacturing plants, 71 biodiesel plants, and 13 “renewable diesel” plants in the U.S. – as well as permit applications for dozens of new facilities and expansions – and reached the following conclusions:

  • HAZARDOUS AIR POLLUTION: Despite their “green” reputation, biofuel factories release almost as much hazardous air pollution as oil refineries, with biofuel plants reporting they emitted 12.9 million pounds of hazardous air pollutants in 2022 (the most recent available year) and oil refineries 14.5 million pounds, according to reporting to EPA’s Toxics Release Inventory.
  • 4 X MORE OF FOUR POLLUTANTS: Biofuel manufacturing plants reported releasing significantly more of four hazardous air pollutants. The biofuel plants reported emitting 7,698,860 pounds of hexane in 2022 (compared to 2,630,758 from oil refineries); 2,117,953 pounds of acetaldehyde (compared to 10,420 from refineries); 357,564 pounds of acrolein (compared to zero from refineries); and 235,125 pounds of formaldehyde (compared to 67,774 from refineries).
  • ACROLEIN: More acrolein is emitted from the biofuels industry than any other industry in the U.S. And the Cargill Inc. ethanol plant in Blair, Nebraska, was the single largest emitter of acrolein in the U.S. in 2022, regardless of industry, reporting the release of 34,489 pounds of a chemical that can cause shortness of breath and irritate the lung and eyes.
  • HEXANE: The Archer Daniels Midland (ADM) ethanol and grain processing plant in Decatur, Illinois – one of the largest ethanol factories in the country – was the single largest emitter of hexane in the U.S. in 2022, regardless of industry, releasing 2.2 million pounds of a pollutant that can damage the nerves and cause dizziness and nausea.
  • FREQUENT VIOLATIONS: More than 41 percent of biofuels plants (98 of 240) violated their air pollution control permits at least once between July 2021 and May 2024, according to a review of EPA’s Enforcement and Compliance History Online database.
  • FAILED SMOKESTACK TESTS: Sixty-five out of 182 biofuel plants with available data (36 percent) failed “stack tests,” over the last five years, which measure the amount of a pollutant to determine if emissions are in compliance with the Clean Air Act.
  • CLIMATE IMPACT: In terms of climate-warming pollution, biofuel plants in the U.S. reported emitting over 33 million metric tons of greenhouse gases in 2022 – as much as 8.5 coal-fired power plants burning fuel around the clock or 27.5 average oil refineries.
  • RAPID GROWTH: After quadrupling the number of biofuel plants in the first decade of this century, the industry continues to grow – with at least 32 new or expanded biofuels facilities now under construction or proposed that would increase biofuel capacity by another 33 percent over 2023 levels. About two thirds of these new facilities and expansions are for “sustainable aviation fuel” that may include jet fuel made from wood or plants.

EIP’s report found that ethanol manufacturing plants enjoy some exemptions from air pollution permitting requirements, making it easier for companies to expand or build new facilities without installing or upgrading pollution controls to reduce emissions of health-damaging air pollutants.

In 2007, EPA removed corn-based ethanol plants from a list of industrial facilities subject to more stringent emission thresholds under the Clean Air Act. As a result, these ethanol plants can emit more than twice as much pollution – up to 250 tons per year instead of 100 tons per year – before they must obtain a major source permit that requires stronger pollution controls.

EIP’s report discusses these exemptions and environmental problems with the biofuel industry, and then focuses on case studies in Iowa, Illinois, California, and Louisiana.

IOWA: Muscatine County, Iowa, is one of the few rural counties whose air quality violates federal ozone standards in the Midwest and the only one in Iowa. Muscatine is home to a Grain Processing Corp. ethanol refinery that has failed air pollution control “stack tests” 16 times over the last five years, according to EPA records. Among other pollutants, the plant reported releasing 113,612 pounds of acetaldehyde in 2022 (third most of any U.S. biofuels plant).

ILLINOIS: The Archer Daniels Midland ethanol facility in Decatur has a poor environmental track record and reported releasing three million pounds of hazardous air pollutants and four million metric tons of greenhouse gases in 2022, the most of any biofuel facility that year in both categories. An explosion at the plant in April 2023 resulted in the hospitalization of three employees.

CALIFORNIA: In the San Francisco Bay area, an oil refinery was converted into a biofuels plant for the Rodeo Renewed Project and faced opposition from local residents, in part because of the air pollution and greenhouse gas emissions from biofuels manufacturing.

LOUISIANA: About four hours north of New Orleans, in Columbia, Louisiana, a company called Louisiana Green Fuels is proposing to build an enormous refinery that would transform trees into jet fuel. However, the company is using emission estimates for its hazardous pollutants based on very limited lab testing of a single gram of wood.


Eliot Clay, Land Use Director at the Illinois Environmental Council, said: “The truth is, contrary to popular misunderstanding, residents in central and southern Illinois live with an alarming level of exposure to toxic industrial emissions.  This EIP report sheds light on the growing need for increased public transparency around the air pollution generated by the biofuels industry so that people living in this part of the state better understand what hazardous air pollutants are actually in the air we breathe.”

Robert Hirschfeld, Director of Water Policy at the Prairie Rivers Network, said: “People near Decatur, IL, are constantly exposed to air pollution that can harm their brains and cause dizziness and nausea. ADM’s ethanol plant also emits more greenhouse gases than places like oil refineries in Illinois. On top of that, corn production for ethanol has resulted in so much pollution that Illinois residents are advised not to swim in, eat fish out of, or drink water from streams and rivers across the state. EPA needs to regulate the facility like it would regulate any other large-scale polluter.”

David Van Gilder, Senior Policy and Legal Director for the Hoosier Environmental Council, said: “This report from the Environmental Integrity Project again reveals the need to promote energy conservation efforts instead of subsidizing industries that significantly contribute to emissions of hazardous air pollution and greenhouse gases. The Hooser Environmental Council supports each of EIP’s five recommendations in this report and HEC strongly urges EPA and the Indiana Department of Environmental Management to strictly enforce existing law to prevent further air quality violations from Indiana ethanol and biofuel facilities.”

Jess Mazour, Sierra Club Iowa Chapter Conservation Program Coordinator, said: “Air pollution from facilities like Grain Processing Corp have gone unchecked for too long. Protecting public health is critically important. We need to hold these polluters to account and we look forward to seeing Iowa’s Department of Natural Resources (DNR) put pollution controls on these plants.”

Buffalo Bruce, Conservation Chair of the Nebraska chapter of the Sierra Club, said: “This report highlights the regulatory failure of the EPA and state environmental agencies to protect the public’s health from harmful air emissions released by the biofuel industry. This report adds to the mounting evidence that biofuel production is only being kept alive by a massive set of federal and state subsidizes and regulations that serve as industrial welfare. The Sierra Club calls for an end to all subsidies supporting industrial agriculture.”

To address the pollution problems from biofuel manufacturing plants, EIP’s report makes the following policy recommendations:

  1. END PERMITTING EXEMPTIONS FOR ETHANOL: EPA should reverse its 2007 decision to relax major source permitting thresholds for ethanol manufacturers that allow these plants to emit more than twice the level of air pollution before needing to install better pollution controls.
  2. BETTER MONITORING AND CONTROL OF POLLUTANTS: EPA should require large biofuel plants to install air pollution monitoring devices along their fencelines to detect the levels of hazardous air pollutants, like acetaldehyde and acrolein, that could be drifting into nearby communities. EPA should also establish an ‘action level’ for these and other highly toxic pollutants, that, if exceeded, would obligate these facilities to identify the sources of the emissions and then fix the problems causing elevated concentrations.
  3. STRONGER ENFORCEMENT OF PERMITS: EPA and state regulatory agencies should more vigorously enforce air pollution control permits for biofuel plants, imposing penalties large enough to discourage future violations and protect downwind communities.
  4. IMPROVE THE ACCURACY OF EMISSIONS REPORTING: Biofuels producers should be required, during the permit review and approval process, to expand their emissions testing and improve the accuracy of their pollution reporting to both EPA and the states.
  5. END BIOFUEL SUBSIDIES AND MANDATES: Biofuels are growing at a rapid rate in part because of government funding and regulatory mandates for blending ethanol into gasoline. But the environmental benefits of these government supports are questionable at best. All existing subsidies and mandates for ethanol – including the renewable fuel standard – should be halted – and attention focused instead on clean energy sources like solar and wind and the infrastructure needed to support them.

The Environmental Integrity Project is a nonprofit organization dedicated to protecting public health and our natural resources by holding polluters and government agencies accountable under the law, advocating for tough but fair environmental standards, and empowering communities fighting for clean air and clean water.

Media contact: Tom Pelton, Environmental Integrity Project (443) 510-2574 or